Currently, overshots are used to externally engage, pack off, and retrieve twisted-off or lost tubing, drill pipe, coupling, tool joints, casing, or other similar fish during oil field operations. The basic design of an overshot consists of a bowl, grapple, and control. Each grapple has a maximum and minimum catch size that it can catch. For the prior art, that range can be 1/32″ over and 3/32″ under the nominal size, resulting in an effective total range of ⅛″. In addition, wide catch overshots have been designed to catch an even larger range of fish. By definition, that range is translated into the range that the seal must be able to seal upon. The prior art utilizes a type of seal known as a Type “A” packer. Although this seal could effectively seal on the fish, the Type A method of sealing, however, is limited to the largest sizes for that overshot assembly. As the desired catch size decreased, a different sealing method is needed, due to the increasing size of the extrusion gap.
Accordingly, there is a need in the art for a non-extrusion subassembly to effectively seal across the increasingly-sized extrusion gaps.